Sampling

There are some protocols for water sampling in aquatic bodies.

Some necessary elements are:

- Clean bottles for the sample

- Electronic equipment for reading basic physicochemical parameters

- Proper clothing

If you are going to perform microbiological sampling, you will need sterile bottles or prefabricated sterile bags.

Sampling example with waterproof half-length feet:

Toxic Assays

Toxicity tests is a methodology to evaluate toxic responses on aquatic organisms, which have been exposed to pollutants.

Some examples of tests:

- Acute toxicity tests:
They are usually used for substances in high concentrations and the observation of the effects in 24-96 hours. Example: Average lethal concentration (LC50)

- Chronic toxicity tests:
For substances at lower concentrations, in a longer observation time, which may be up to 3 months. Example: inhibition of growth after a period of time.

Water Quality Methods

Currently there are several methods to measure the quality of water in aquatic bodies.

The traditional method is through physicochemical indicators. With this method it is evaluated that the parameters do not exceed the limits established in the regulations, for the protection of aquatic life. However, it is not possible to evaluate the biological effect on aquatic organisms.

Biological methods allow to evaluate responses on aquatic organisms, through different evaluations, such as:

- Indicator species: tolerant or sensitive to pollutants, based on observations in the field.

- Structure of the community of organisms in a determined place, with respect to reference conditions

- Physiological changes

- Acute toxicity

- Chronic toxicity

- Other effects

Normas mexicanas agua

Estas son las principales normas mexicanas que establecen límites de control en cuerpos cuerpos acuáticos y alcantarillado.

- NORMA Oficial Mexicana NOM-001-ECOL-1996, Que establece los lí­mites máximos permisibles de contaminantes en las descargas de aguas residuales en aguas y bienes nacionales.

Resumen: Límites descarga en cuerpos acuáticos  LINK: DOF NOM 001

- NOM 002 Establece los límites máximos permisibles de contaminantes en las descargas de aguas residuales a los sistemas de alcantarillado urbano o municipal. (03 Jun 1998)

Resumen: Límites descarga en alcantarillado LINK: DOF NOM 002

- ACUERDO por el que se establecen los Criterios Ecológicos de Calidad del Aguas CE-CCA-001/89

Resumen: Niveles guía de referencia para protección de la vida acuática LINK: CE89

Este acuerdo, aunque no es Norma Oficial Mexicana, es importante por ser la única en establecer unos criterios de referencia para los cuerpos acuáticos y la protección de la vida acuática, en México.

Nota: Posteriormente publicaré otras normas de importancia